White Paper:

Follow-up Efforts on SEC-00192 RFP Tritium Issues

By

J. S. Bogard, E. M. Brackett, Mutty Sharfi, and Dan Stempfley

(Rev. 0, 06-25-13)

This is a summary of the tritium follow-up effort performed by DCAS and ORAUT in support of 

the SEC-00192 Rocky Flats Plant SEC Evaluation Report presented to the Advisory Board in 

September 2012. As part of the follow-up, additional document data captures and personnel 

interviews were performed (classified and unclassified). In addition to follow-up on the 

existence of tritium on site and associated personnel exposures, the follow-up also focused on 

the specific areas of tritium bubbler sampling, shipping container tritium surveys, and sampling 

analysis performed in Building 123. These follow-up efforts were performed to validate the 

tritium bounding method for the SEC-00192 RFP ER (which uses information from the 1973 

tritium incident as the maximum exposure scenario), and to provide more precise estimates of 

doses due to tritium.

ER FOLLOW-UP

A review of all RFP-related SRDB documents was performed to determine if any documents 

existed in that dataset that could expand on any of the issues raised regarding tritium. The 

documents relating to tritium monitoring at RFP were identified, including some tritium bubbler 

results, and some indication of tritium contamination surveys. There are multiple documents 

regarding four significant incident-related tritium releases that occurred in 1968, 1973, 1974, 

and 1977 (SRDB Ref ID: 8265, 8790, 24164, 24165, 24167, 110900, 110901, and 110903). There 

are also post-1977 documents that confirm continued monitoring of tritium releases and 

residual tritium as a result of these four earlier releases. There is also an SRDB document that 

provides information on post-1977 stack releases occurring in 1981 and 1986; both releases 

were considered small with no impact to site personnel or the immediate surrounding area 

(SRDB Ref ID: 110900). While some of the documents corroborated the classified interview 

issues addressed in the following sections of this white paper (i.e., bubblers and tritium 

contamination surveys), it does not appear that any of the new information supports the notion 

that there were any tritium levels that exceeded the 1973 incident. Therefore, ORAUT finds no

evidence disputing the use of the 1973 incident data as the bounding estimate for tritium at 

RFP, as presented in the SEC-00192 RFP ER.

This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues

This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 2 of 38

As stated in the SEC-00192 ER, RFP operations that were related to, or had potential exposure 

impacts associated with tritium included neutron generator operations (i.e., the use of tritiated 

targets), and returned pit operations. Subsequent post-ER classified interviews identified 

shipping container handling as a potential exposure source. The following was learned:

 The follow-up effort corroborated in at least one interview (SRDB 122907) and in two 

documents (SRDB 118369; 117274) the point made in the SEC-00192 ER that the stainless 

steel reservoir operation was a construction operation before the introduction of tritium, 

which occurred at other sites. RFP was responsible constructing the reservoirs and shipping 

them to other locations where they were filled/used. 

 

 The follow-up effort corroborated that the neutron generator tritium target sources did not 

represent a source larger than the one represented in the 1973 tritium incident. 

 The tritium-contaminated pits and shipping containers are considered directly related 

because the shipping container tritium was a result of tritium from the pits loaded in the 

containers. Because of potential classification issues. theThe assessment of this issue will 

be addressed later in this document under the more general term Shipping Containers 

rather than the term Pits. 

 A follow-up effort was directed to determine if there are any other scenarios with the 

potential to exceed the SEC-00192 RFP ER bounding approach. These scenarios are being 

assessed as part of the pre-1973 tritium shipping container exposure evaluation (discussed 

later).

The indications found in the available documentation, and provided by the majority of 

interviewees, was that RFP did not work with tritium as a normal or usual process, and 

therefore, did not expect it on site. The RFP radiological program did very little monitoring for 

tritium prior to the 1973 incident because they felt they had limited tritium exposure potential. 

Changes to the program related to tritium monitoring were implemented as a result of the 

1973 incident. It has been corroborated that tritium bubbler monitoring did exist on site as 

part of the usual RFP air monitoring program before and after the 1973 tritium incident (SRDB 

122907); however, the current information does not indicate how long before the 1973 

incident bubblers existed on site. The available bubbler monitoring data is being evaluated for 

its applicability in dose reconstructions.
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues

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Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

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document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 3 of 38

As indicated in the SEC-00192 ER, the site implemented a routine tritium bioassay program 

after the 1973 tritium incident, but discontinued the routine program in 1975 due to lack of 

positive bioassay results. The program was subsequently implemented on an as-needed or 

as-identified basis. This situation was corroborated in at least one personnel interview 

performed during this follow-up effort (SRDB 122907).

TRITIUM BUBBLERS

Significant information on the bubbler monitors was discovered during the additional follow-up 

data capture efforts. There is some documentation in the SRDB that discusses the use of 

tritium bubblers. Based on the available data, including the most recent information 

(schematics and pictures of the tritium air sampling and monitoring equipment and processes 

[SRDB 122779 through 122791]), there was a program that included the use of tritium bubblers 

to monitor enclosed and exhaust systems for tritium (SRDB 122466). As previously discussed, 

the exact start date for the use of bubblers has not been confirmed, but they did exist on site 

before the 1973 incident (SRDB 122907). Most individuals interviewed were not well-informed 

on bubbler use or operation.

The SRDB contains some tritium bubbler results (SRDB 111095 and 122712) as well as detailed 

schematics and pictures of the units (SRDB Ref ID’s: 122691, 122692, 122693, 122787, 122788, 

122789, and 122790). Based on these results, information discovered during the follow-up 

research, and the interviews there is nothing to support the occurrence of a release event more 

significant than the 1973 incident. Table 1 presents a summary of the Rocky Flats tritium 

bubbler information contained in the SRDB.
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues

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Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 4 of 38

Table 1: Rocky Flats Tritium Bubbler Information in the SRDB

SRDB Ref ID Year File Description Comments

Category: Tritium Monitoring Results, Procedures, and Occurrences

17824 1990-

1991 Occurrence reports

Contains two occurrence reports involving 

inoperable bubblers, and one report of a Triton 

tritium air monitor that was shut off. None of 

the occurrences involved tritium releases.

24164 1976-

1983 Tritium inventories and effluents

Contains: an evaluation of tritium-release 

potential from a proposed neutron crate counter 

(1983); elevated tritium effluents from Bldg 

776/777 (January 1981); estimated inventory of 

tritium as surface contamination in glove boxes, 

ducts, and exhaust plenums in Bldg 776/777 

(1980); evaluation of ethylene glycol in place of 

water in tritium bubblers (1978); special study of 

tritium in ambient air (1976); a report, 

“Estimates of Maximum Tritium Releases to the 

Atmosphere from Operations at the Rocky Flats 

Plant” (1976); and a Call Report indicating that 

0.058 μCi of tritium would probably be vented to 

the atmosphere for an experiment on May 20, 

1974.

24307 1986 Procedure for effluent and room air 

tritium sampling Operating procedure

111095 1977-

1981 Tritium bubbler sampling results

Log of analytical results for bubblers in operating 

areas, including room air and near downdraft 

tables. Most results are <100 pCi/m3, but results 

exceed 1,000 pCi/m3on several occasions in 

Bldg 559 - Rm 102, and in Bldg 881- Rm 283. 

Highest result appears to be 89,230 pCi/m3in 

Bldg 771 for the period May 11-18, 1978.

122466 2013 Documented interview with [Name 

redacted]

Includes a discussion of the different 

laboratories at Rocky Flats for analyzing tritium 

and other radionuclides in samples.

122712 1998 Lab report - tritium activity in bubblers

Detailed analytical report from Thermo NUtech, 

including sample activity, counting uncertainty, 

detection limit, and total propagated 

uncertainty.
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues

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Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 5 of 38

Table 1: Rocky Flats Tritium Bubbler Information in the SRDB

SRDB Ref ID Year File Description Comments

122907;

24167 2013 Documented interview with [Name redacted]; 1973 incident report

Includes a discussion of the tritiated targets for 

laser fusion experiments and corroboration that 

bubblers were in use at several Rocky Flats 

locations prior to the 1973 tritium release 

incident.

Category: Tritium Sampler Photos and Design Documents

122691 1973 Photos – tritium operations at Dow

Relevance of photos to tritium monitoring or 

tritium operations is not apparent, except for 

one photo of a Triton tritium monitor.

122692 1977 Photos - tritium monitoring

Good photos of sampling fixture for sealed cans 

and drums, Triton Model 955B tritium monitor, 

and bubblers mounted outside a glove box for 

sampling glove box air.

122693 1983 Photos – tritium air sampling station

Labeled tritium sampling assembly showing 

building number, air flow rates, and water 

volume.

122779 1974 Drawing 1 of 8 - Tritium and iodine 

sampler assembly Engineering drawing

122780 1974 Drawing 2 of 8 - Tritium and iodine 

sampler assembly Engineering drawing

122781 1974 Drawing - Environmental tritium and 

radioiodine sampler details Engineering drawing

122782 1974 Drawing - Environmental tritium and 

radioiodine sampler wiring diagram Engineering drawing

122783 1974 Drawing - Environmental tritium and 

radioiodine sampler mounting detail Engineering drawing

122784 1974

Drawing - Environmental tritium and 

radioiodine sampler onsite electrical 

hookup

Engineering drawing

122785 1974

Drawing - Environmental tritium and 

radioiodine sampler offsite electrical 

hookup

Engineering drawing

122786 1974

Drawing - Environmental tritium and 

radioiodine sampler onsite and offsite 

electrical hookup

Engineering drawing

122787 1978 Drawing – Tritium detector assembly Engineering drawing
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues

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Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 6 of 38

Table 1: Rocky Flats Tritium Bubbler Information in the SRDB

SRDB Ref ID Year File Description Comments

122788 1978 Drawing – Tritium detector details (1) Engineering drawing

122789 1978 Drawing – Tritium detector details (2) Engineering drawing

122790 1978 Drawing – Tritium detector details (3) Engineering drawing

122791 1978 Drawing - Tritium detector flow 

diagram Engineering drawing

SHIPPING CONTAINERS

As part of the follow-up, additional research was performed regarding the issue of tritium 

contamination in shipping containers. This issue arose from one of the classified interviews 

(SRDB 122516). Tritium contamination in shipping containers was corroborated in an SRDB 

document (SRDB Ref ID: 111301); however, no actual contamination surveys have been found. 

The follow-up survey requirements and processes were corroborated in a follow-up interview 

in which the interviewee discussed implementing the shipping container tritium survey 

program in response to the 1973 incident (SRDB 122907). During that interview, the 

interviewee said that no tritium contamination was ever found. Other classified interviewees 

indicated that they had heard about shipping-container contamination, but they had no direct 

experience of it. A worst-case situation analysis of potential shipping-container contamination 

levels has been performed for comparison with the SEC-00192 ER bounding analysis in order to 

validate the ER’s bounding exposure scenario and to provide a more precise estimate for 

tritium dose prior to 1973. This analysis is provided in Appendix 1.

BUILDING 123

Analytical capability existed in both the production areas and in Building 123 (SRDB 122625), 

which housed the laboratories supporting worker health and safety (Industrial Hygiene and 

Health Physics) as well as the environmental programs (SRDB 122627). Samples collected in the 

production areas may have been analyzed either in the production laboratories or in Building 

123, depending on the anticipated level of analytes and the potential for contamination with 

plutonium or uranium, for which strong contamination-control practices were in place. Tritium 

samples from stack exhausts, which were filtered several times before sampling and release to 

the environment, were typically analyzed in Building 123. Samples collected in the work areas 
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues

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Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 7 of 38

were analyzed in a production area laboratory to eliminate the possibility of introducing 

plutonium contamination into the Building 123 lab (SRDB 122627). Samples with a high 

likelihood of elevated tritium content might also be analyzed in a production lab to prevent 

tritium contamination in the low-level Building 123 laboratories (SRDB 122624). 

Some effort was made prior to 1973 to use commercially-available tritium monitoring 

equipment (e.g., the vibrating reed spectrometer and tritium sniffers) (SRDB 110885; 122623; 

122670; 122671) or to develop an in-house capability (through development of specialized ion 

chambers or tritium concentration techniques, such as silica gel traps [SRDB 24648; 24680]). 

Liquid scintillation counting was reportedly used for quantitative analysis of a variety of 

radioactive materials in the production areas; it quickly became the technique of choice for 

tritium sample analysis after the 1973 environmental tritium release. Tritium sniffers continued 

to be used to indicate elevated tritium in the workplace, but they did not provide quantitative 

data of record.

No results for tritium samples analyzed in the production areas have been captured, and only 

limited data are available from the Building 123 laboratories. ORAUT’s understanding of the 

criteria for determining where tritium samples were analyzed comes solely from interviews 

with former Rocky Flats Plant employees.

CONCLUSION

The additional documents and interviews obtained during the post-ER follow-up efforts provide 

additional evidence of the potential for tritium exposures. However, the information also 

supports the case that estimates of potential tritium exposure that could have occurred prior to 

1973 are bounded by the exposure estimate for the 1973 event, and that more precise 

estimates are feasible.

Table 2 below lists the follow-up actions performed in support of SEC-00192. Table 3 below

lists the follow-up interviews performed in support of SEC-00192.
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues

This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 8 of 38

ADDITIONAL ASSESSMENTS: APPENDIX 1

In light of the additional information and data gathered during the follow-up effort, NIOSH 

requested that ORAUT evaluate the available documentation and data to: (1) analyze RFP 

tritium exposures for 1959-1973; (2) determine the best approach for dose assignment for 1973 

and later; and then (3) produce an example tritium dose reconstruction employing the best 

approach determined in the analysis. The results of this assessment are provided in 

Appendix 1.

Table 2: Follow-up Actions Performed in Support of SEC-00192

Date Activity Locationa

10/03/2012 Secure Discussions NIOSH (Cincinnati OH)

10/28/2012 Data Capture LANL (Los Alamos NM)

11/06/2012 

through 

11/07/2012

Eleven secure interviews with former RFP employees DOE-EMCBC (Denver CO)

01/15/2013 

through 

01/31/2013

Eight follow-up telephone interviews with former RFP 

employees

02/03/2013 Data Capture DOE-LM (Westminster CO)

EMCBC (Denver CO)

02/22/2013 Data Capture OSTI (Oak Ridge)

02/25/2013 Secure Discussions NIOSH (Cincinnati OH)

05/30/2013 Reconstructing Rocky Flats Tritium Doses Pre- and Post1973 (see Appendix 1) ORAUT (Cincinnati OH)

a

DOE-EMCBC (Denver), LANL (Los Alamos), and OSTI (Oak Ridge) are sites where reviews of classified material were 

performed. Secure interviews were conducted at DOE-EMCBC.
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues

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Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

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document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 9 of 38

Table 3: Follow-up Interviews Performed in Support of SEC-00192

Site Interview Topic Interview Date SRDB Ref ID

Rocky Flats, SEC-00192 Tritium (DFC)* 11/6/2012 122515

Rocky Flats, SEC-00192 Tritium (DFC) 11/6/2012 122553

Rocky Flats, SEC-00192 Tritium (DFC) 11/6/2012 122666

Rocky Flats, SEC-00192 Tritium (DFC) 11/6/2012 122667

Rocky Flats, SEC-00192 Tritium (DFC) 11/6/2012 122668

Rocky Flats, SEC-00192 Tritium (DFC) 11/6/2012 122551

Rocky Flats, SEC-00192 Tritium (DFC) 11/6/2012 122550

Rocky Flats, SEC-00192 Tritium (DFC) 11/7/2012 122517

Rocky Flats, SEC-00192 Tritium (DFC) 11/7/2012 122516

Rocky Flats, SEC-00192 Tritium (DFC) 11/7/2012 122669

Rocky Flats, SEC-00192 Tritium Building 123 1/15/2013 122627

Rocky Flats, SEC-00192 Tritium Building 123 1/15/2013 122628

Rocky Flats, SEC-00192 Tritium Building 123 1/16/2013 122624

Rocky Flats, SEC-00192 Tritium Building 123 1/18/2013 122625

Rocky Flats, SEC-00192 Tritium Building 123 1/22/2013 122629

Rocky Flats, SEC-00192 Tritium Building 123 1/22/2013 122623

Rocky Flats, SEC-00192 Tritium Building 123 1/23/2013 122626

Rocky Flats, SEC-00192 Tritium Building 123 1/31/2013 122670

Rocky Flats, SEC-00192 Tritium Building 123 1/31/2013 122671

* DFC = Denver Federal Center where secure interviews regarding tritium were conducted.
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues

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Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

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document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 10 of 38

Appendix 1:

Reconstructing Rocky Flats Tritium Doses Pre- and Post-1973

by

J. S. Bogard, E. M. Brackett, Mutty Sharfi

Introduction

The potential for tritium exposure to Rocky Flats personnel was not considered significant until 

an unexpected release occurred in April 1973. Because tritium monitoring was not rigorous 

before this event, NIOSH requested that ORAUT perform a follow-up effort to validate the 

tritium bounding method for the SEC-00192 RFP ER, which uses information from the 1973 

tritium incident as the maximum exposure scenario. ORAUT conducted additional document 

data captures and personnel interviews regarding the existence of tritium on site and 

associated personnel exposures as well as follow-up on tritium bubbler sampling, shipping 

container tritium surveys, and sampling analysis performed in Building 123.

In light of the additional information and data gathered during the follow-up effort, NIOSH 

requested that ORAUT evaluate the available documentation and data to: (1) analyze RFP 

tritium exposures for 1959-1973; (2) determine the best approach for dose assignment for 1973 

and later; and then (3) produce an example tritium dose reconstruction employing the best 

approach determined in this analysis. This white paper presents the results of these three 

efforts:

 PART I: Analysis of Rocky Flats Tritium Exposures for 1959-1973 by J. S. Bogard

 PART II: Rocky Flats Tritium Dose Assignment for 1973 and Later by E. M. Brackett

Attachment A: Rocky Flats 1973 H-3 Dose Assignment by E. M. Brackett

 PART III: Example RFP Tritium Dose Reconstruction by Mutty Sharfi
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues

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Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

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document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 11 of 38

PART I:

Analysis of Rocky Flats

Tritium Exposures for 1959-1973

by

J. S. Bogard

Tritium Monitoring Data Prior to 1973

Although tritium was used as a boost gas in weapons and as target material in neutron 

generators, it was not processed or handled in any significant quantities at Rocky Flats. Tritium 

was monitored in the environment around the site for a time, but that monitoring ceased and 

was left to the State of Colorado for a brief period preceding an environmental release that 

occurred in April 1973. No analytical records have been captured by NIOSH that might help 

establish the Rocky Flats workplace tritium environment prior to that time.

The management of Rocky Flats woke abruptly to the potential for tritium workplace and 

environmental contamination with the release in April 1973 of 500 Ci - 2,000 Ci of tritium, 

primarily from Building 779A, and its eventual detection in waters draining into a reservoir

serving as a municipal drinking water supply (SRDB Ref ID: 110941; 111269; 111284). The 

release also resulted in tritium exposure to a small number of Rocky Flats personnel. 

Subsequent workplace monitoring and personnel bioassay was implemented, in part to 

establish the baseline tritium environment against which future incidents could be evaluated. A 

smaller and less-impactful tritium release occurred in September 1974 from Building 777; the 

subsequent investigation report (SRDB Ref ID: 8790) includes release details along with

summaries of tritium workplace monitoring results prior to the incident for comparison. These 

data provide the basis for a model for bounding chronic tritium exposures to workers and of

smaller, less-notable tritium releases that might have occurred prior to 1973.

Several factors single out the 1973 tritium release as bounding for the entire history of Rocky 

Flats operations. These factors include the large quantity of tritium involved, the chemical form 

of the released tritium, and the meteorological conditions at the time of the release. Other 

documented releases involved smaller quantities of elemental tritium, having a much smaller 

dose conversion factor than the tritium oxide released in 1973. Bounds for personnel tritium 

exposures after the 1973 release can be developed based on measurement results, since 

personnel bioassay, air sampling, and workplace contamination monitoring for tritium became 
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues

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Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

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document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 12 of 38

more common after that release. There are only very limited tritium measurement results prior 

to 1973 because tritium was not perceived as a radionuclide of occupational or environmental 

interest at Rocky Flats. Bounding tritium exposures for the pre-1973 period are more difficult 

to develop as a result of this lack of measurement data.

According to the ChemRisk report (SRDB 8017), there was no environmental monitoring for 

tritium prior to 1970, and little in the way of workplace monitoring until after the 1973 tritium 

release; therefore, evidence of tritium releases prior to 1973 is primarily anecdotal. A 600-Ci 

release of elemental tritium (from a different source than the 1973 release) occurred in 1968. 

The ChemRisk report said the following with regard to possible releases from tritiated Pu 

shipments (SRDB 8017, pdf p. 285):

The 1973 findings associated with the tritiated plutonium initiated an investigation of other 

possible similar shipments and processing of tritiated plutonium. The investigation 

discovered three other shipments with maximum estimated tritium releases of 57 Ci (April 

1969), 40 Ci (March 1971), and 29 Ci (November 1971).

The reported investigation and the documented 1968 release of elemental tritium are the only 

sources of information about other possible releases. The 1968 release was elemental tritium

with no significant environmental or personnel exposure. None of the three identified 

potential releases from tritiated Pu was near the magnitude of the 1973 release. There is no 

evidence of a tritium release comparable to the magnitude and impact of the 1973 release prior 

to that year.

Source of Data for the pre-1973 Period

Despite the lack of measurement data, it is possible to develop pre-1973 tritium exposure 

bounds based on measurement results provided in a Rocky Flats Area Office (RFAO) report 

issued subsequent to a tritium release in one of the Rocky Flats production buildings on 

August 30, 1974 (SRDB Ref ID: 8790). The information contained in this report includes 

measurement data (i.e., results from air samples, surface contamination surveys, and bioassay) 

from the production area where the release occurred as well as comparison data from other 

areas prior to, during, and after the release. Several factors support the use of these data as 

surrogates for bounding the tritium environment at Rocky Flats prior to 1973:

1. Background tritium levels immediately prior to the incident described in the RFAO report, 

although undoubtedly elevated since the more significant 1973 release, were well below 
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Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

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Page 13 of 38

dosimetrically-significant values and can be considered as fairly representative of typical

background levels for this analysis. The background tritium levels monitored in the months 

prior to the 1974 incident are consistent with internal radiation doses from tritium of well 

under 1 mrem annually. They are dosimetrically insignificant in this sense.

2. The quantity of tritium released (1.5 Ci) was significantly less than that released in 1973, 

and is probably more typical of potential undocumented releases in work areas –

particularly those resulting from opening contaminated shipping containers.

The 1974 1.5-Ci tritium release is the only documented release from a shipping container in 

the Rocky Flats workplace. It is taken to be typical since there are no other such 

documented releases to use in forming the model. There is documented concern about 

tritium releases, as shown in the following quote from the ChemRisk report (SDRB 8017, 

pdf p. 38):

As early as 1962, Rocky Flats maintained instruments for detection of tritium gas in 

particular work areas of the plant because operations have sometimes resulted in the 

storage of tritium containers.

The instruments available to Rocky Flats at that time were only semi-quantitative for 

indicating the presence of tritium; NIOSH has captured no records of these results.

Because NIOSH has only identified six documented releases from 1968-1974 (an average of 

1 per year), the application of a daily release would be a significant/bounding overestimate 

of the number of RFP tritium releases.

3. Tritium was released to the workplace environment, and not in a glovebox.

4. The release involved elemental tritium (HT, T2), and not tritium oxide (HTO)1.

 

1

The impact of the 1973 tritium release was largely due both to the quantity (500 Ci – 2,000 Ci) and the 

chemical form (HTO) of the material. The presence of tritium oxide in the 1973 release resulted from peculiarities 

of the plutonium recovery operation from which it was generated. There is no indication that any other tritium 

release at Rocky Flats involved the oxide. Tritium in its elemental form (HT, T2) is far more likely to have been a 

contaminant at Rocky Flats because of the nature of its possible source terms – tritiated accelerator targets 

(neutron generators), plutonium hydride in recovery operations, and boost gas in returned reservoirs or pits.
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5. The tritium was released from a contaminated shipping container which was procured by 

Rocky Flats in 1970 and can be taken as representative of shipping containers in use prior to 

1973.

As stated in the response to Item 2, the 1974 1.5-Ci tritium release is the only documented

release from a shipping container in the Rocky Flats workplace. It is taken to be typical 

since there are no other such documented releases to use in forming the model. There is 

documented concern about such releases, as shown in the following quote from the 

ChemRisk report (SDRB 8017, pdf p. 38):

As early as 1962, Rocky Flats maintained instruments for detection of tritium gas in 

particular work areas of the plant because operations have sometimes resulted in the 

storage of tritium containers.

The instruments available to Rocky Flats at that time were only semi-quantitative for 

indicating the presence of tritium; NIOSH has captured no records of these results.

Because NIOSH has only identified six documented releases from 1968-1974 (an average of 

1 per year), the application of a daily release would be a significant/bounding overestimate 

of the number of RFP tritium releases.

6. The incident occurred close enough in time to the 1973 tritium release that work practices 

and controls were likely more similar to those prior to 1973 than to those even a year or 

two later, as procedures and controls evolved with greater sensitivity to the potential for 

tritium contamination.

The RFAO report provides the best source of monitoring data for use in bounding both chronic 

and accidental tritium exposures to Rocky Flats personnel prior to the unique circumstances of 

the 1973 release.

The RFAO report states that elevated tritium concentrations were detected in air samples from 

Room 452 (Special Assembly Area) in Building 777 and from the Building 205 exhaust plenum 

servicing Building 776/777 over the period of August 29 – September 4, 1974 (SRDB Ref ID: 

8790, pdf p. 9). Subsequent sampling and investigation of the elevated sample results 

concluded that about 1.5 Ci of tritium was released from the exhaust system of Room 452, 

Building 777, when a shipping container (referred to as a “pressure cooker”) received in July 

1974 from Battelle Pacific Northwest Laboratory (BNW) was opened on a downdraft table in 
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Room 452 on August 30 (SRDB Ref ID: 8790, pdf pp. 36-39). No elevated environmental tritium 

levels were detected as a result of the incident, but workplace tritium levels seven times the 

applicable Radiological Control Guide were detected in air samples collected on August 30 in 

Room 452 adjacent to the downdraft table, with average concentrations for the work week 

about 1.5 times the guidelines. Table A-1 shows the reported values.

Table A-1: Reported Tritium Air Concentrations (μCi/m3) from the August 30, 1974 Release

Sampling Reference Plenum 205, Bldg. 776/777aRoom 452, Bldg. 777

Normal Concentrations <1×10-2<1×10-2

August 29-30, 1974 0.148 37.7

September 3-4, 1974 2.51 1.1

Source: SRDB 8790, pdf pp. 93-96

a

The Special Assembly Glovebox Line in Room 452, Building 777, was normally served by Plenum 206, but exhaust 

air from this area was vented through Plenum 205 from February 11 – August 7, 1974, while a new Plenum 206 

was constructed. A tritium air sampler for Plenum 206 was installed on August 30, 1974, but showed no elevated 

results. However, both Plenums 205 and Plenum 206 showed elevated tritium removable contamination (SRDB 

8790, pdf pp. 74-82).

An air sampler located near the downdraft table in Room 452 indicated a tritium air 

concentration of 4.9×10-3μCi/m3on August 29 and 37.7 μCi/m3on August 30. The applicable 

Radioactive Concentration Guideline at the time was 5 μCi/m3. Two “pressure cookers” were 

opened at the downdraft table, coincident with the elevated tritium-in-air measurements, and 

were smear-sampled for removable tritium contamination. One cooker showed smear levels of 

1.16×10-2μCi; the other showed 3.43×102μCi and was presumed to be the source of the 

gaseous tritium release.

Air Sample Results

Results from air samples collected daily in Room 452, Building 777, are available from June 3 to 

September 11, 1974. The air sampler was located near the downdraft table entry to the Special 

Assembly Line where the tritium contaminated “pressure cooker” was opened and was the only 

tritium air sampler in Building 777 at the time. Room air samples were collected in a water 
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Page 16 of 38

bubbler during the day shift (approximately 6 or 8 hours sampling time) at an air flow rate of 

2 L/min. Individual results are shown in Table A-2 (SRDB: 8790, pdf pp. 87-89).

Table A-2: Tritium Activity Concentrations in Room Air: Rm. 452 - Special Assembly - Bldg. 777

Analysis Date 

(1974) [

3

H] (pCi/m3)

Analysis Date 

(1974) [

3

H] (pCi/m3)

Analysis Date 

(1974) [

3

H] (pCi/m3)

3-Jun 9,428 8-Jul 3,872 8-Aug 628

5-Jun 12,121 5-Jul 3,030 12-Aug 1,256

4-Jun 20,370 3-Jul 4,655 13-Aug 1,301

7-Jan 5,892 10-Jul 2,602 16-Aug --

6-Jun 16,498 9-Jul 2,512 20-Aug 2,439

14-Jun 5,387 11-Jul 4,553 21-Aug 3,140

13-Jun 4,553 17-Jul 21,022 22-Aug 3,298

12-Jun 12,358 16-Jul 5,040 23-Aug --

11-Jun 13,972 15-Jul 6,742 26-Aug 2,927

11-Jun 10,894 19-Jul 5,041 27-Aug 3,089

21-Jun 4,348 18-Jul 4,209 28-Aug 4,874

20-Jun 4,553 24-Jul 1,010 29-Aug 3,986

19-Jun 4,414 23-Jul 4,866 30-Aug 37,676,609

18-Jun 5,781 22-Jul 4,866 3-Sep 1,098,901

17-Jun 6,829 29-Jul 2,512 4-Sep 8,477

26-Jun 4,519 26-Jul 2,118 5-Sep 5,108

25-Jun -- 25-Jul 3,089 6-Sep --

24-Jun -- 1-Aug 1,842 9-Sep 3,030

2-Jul 3,454 30-Jul 1,727 10-Sep 3,140

1-Jul 4,348 1-Aug 2,269 11-Sep 2,898

27-Jun 5,366 7-Aug 1,179

27-Jun 4,553 5-Aug 2,512

Source: SRDB: 8790, pdf pp. 87-89

The average and standard deviation of daily air sample results prior to August 30, the day of the 

tritium release from the contaminated shipping container, are (5343 ± 4518) pCi/m3. The result 

on August 30 is 37,676,609 pCi/m3, and the sample taken on September 3 indicated a tritium 

concentration in the room air of 1,098,901 pCi/m3. However, the September 3 result is suspect 

because the sample was collected in the same vessel that was used on August 30 and which 
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had not been cleaned. Smear surveys of Room 452 on September 3 failed to show significant 

tritium contamination (SRDB: 8790, pdf pp. 37-38). Tritium levels in Building 777 were known 

to be somewhat elevated over normal background because of residual contamination present 

since the 1973 tritium release. 

Bioassay Results

The practice of pulling a sample of air from within shipping containers through a tritium air 

monitor to check for contamination was implemented after the 1973 tritium release. This 

practice was discontinued after urinary tritium results in the range of 0.75 μCi/L – 1.3 μCi/L 

were detected in May 1974 for the [redacted for privacy]who performed the monitoring. The 

[redacted for privacy] urinary tritium dropped to less than 0.1 μCi/L beginning in early July 1974 

(SRDB 8790, pdf pp. 18-19).

All employees who worked in Room 452, Building 777, submitted urine samples after the 

August 30 tritium release, with a high result of 32,320 pCi/L. Table A-3 shows individual results

(SRDB 8790, pdf p. 90).

Table A-3: Tritium Urinalysis Results - Exposed Workers and Others, August 30, 1974

Worker ID Area Urinary Tritium (pCi/L) Uncertainty (pCi/L)

[redacted] 777 32320 ± 6170

[redacted] 777 25610 ± 6100

[redacted] 779 24000 ---

[redacted] 777 22370 ± 5800

[redacted] 777 21600 ± 5800

[redacted] 707 17000 ---

[redacted] 777 15740 ± 6100

[redacted] 777 15730 ± 5640

[redacted] 779 14000 ---

[redacted] 707 13700 ± 5370

[redacted] 123 630 ± 580

Non-Occupational (Denver) 470 ---

Source: SRDB 8790, pdf p. 90

Three hyphens (---) = Value not provided.
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The report indicates that both a Denver resident and a [redacted for privacy]employee who did 

not work in radioactive material-handling areas were sampled with results 

< 0.01 μCi/L (<10,000 pCi/L). The Denver resident is identified in Table 3, and Worker ID 

[redacted for privacy] is believed, by implication, to be the [redacted for privacy] nonradiological worker.

Work Area Smear Surveys

Over 200 smear results for tritium are tabulated in the RFAO report (SRDB 8790, pdf pp. 74-82). 

Most appear to be surveys inside glove boxes, but there are also workplace area results that 

can be used as indicators of likely sources of internal contamination of workers following an 

event such as the one in August 1974. The workplace smear results are shown in Table A-4.

Table A-4: Tritium Smear Surveys - Work Areas in Buildings 776-777

Date Bldg/Room Location Maximum Smear (pCi)

9/6/74 776-205 205 Plenum - cold side < 100

9/6/74 776-206 206 Plenum - cold side < 100

9/6/74 777-452 206-532 - top of box < 100

9/6/74 777-430 E.S. Welder 353,000

9/6/74 777-437 Penthouse < 100

9/6/74 777-437 A-1 110,000

9/6/74 777-437 A-2 4,800

9/6/74 777-437 A-3 9,400

9/6/74 777-463 A-5 1,200

9/6/74 777-463 Conveyor Line 7,900

9/6/74 777-463 A-7 7,700

9/9/74 776-205 205 Plenum (hot side) 211,000

9/9/74 776-206 206 Plenum (hot side) 1,230,000

9/10/74 776 - Size Reduction Floor < 500

9/10/74 776-201 Floor 1,100

9/11/74 777-452 Floor at J-24 460

9/11/74 777-452 Floor at K-24 470

9/11/74 777-452 Floor at L-24 640

9/11/74 777-452 Floor at M-24 780

9/11/74 777-452 Floor at K-25 560
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Page 19 of 38

Table A-4: Tritium Smear Surveys - Work Areas in Buildings 776-777

Date Bldg/Room Location Maximum Smear (pCi)

9/11/74 777-452 Floor at J-25 950

9/11/74 776-250 Plenum Floor < 100

9/11/74 776-250 Plenum Fan < 100

9/11/74 776-252 Plenum Floor 465

9/11/74 776-252 Plenum Filter 1,636

9/11/74 776-S-8 Plenum Filter < 100

9/11/74 776-S-8 Plenum Deep Beds < 100

9/11/74 776-S-7 Plenum Filter < 100

9/11/74 776-S-7 Plenum Floor < 100

9/11/74 776-S-4 Plenum Filter < 100

9/11/74 776-251 Plenum Floor 3,625

9/11/74 776-251 Plenum Filter 3,603

9/11/74 776-440 Floor 1,000

9/11/74 776-432 Floor K-20 500

9/11/74 776-432 Floor H-19 1,460

9/11/74 776-432 Floor H-20 710

9/11/74 776-432 Floor K-19 520

9/11/74 776-201 #1 System Kathene 160,000

9/11/74 776-201 #4 System Kathene 400,000

9/11/74 776-201 #3/7 System Kathene 450,000

9/11/74 776-201 #8 System Kathene 140,000

9/11/74 776-201 GBDA System Kathene 400,000

Source: SRDB 8790, pdf pp. 74-82

The exhaust plenums and the Kathabar air driers (which use a lithium chloride solution called 

Kathene) appear to have collected the greatest amount of tritium after the release. Workers 

responsible for changing filters in the plenums or recharging the Kathabar systems would 

appear to be at greatest risk for tritium uptake after the initial release.

Assessment of the 1974 Incident

The 1.5-Ci tritium release from a contaminated shipping container occurred on August 30, 

1974. The RFAO report provides air survey, bioassay, and smear survey results (SRDB 8790). 

Specific urine sample collection dates were not included in the report but data were matched 
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Page 20 of 38

to two NOCTS claims, which reported a collection date of September 5, 1974. A dose 

assessment was performed using the Integrated Modules for Bioassay Analysis (IMBA) 

software. An intake date of August 30, 1974 was assumed, and the largest reported result 

collected after the incident, 36,320 pCi/L, was used. There was a slight discrepancy (one digit) 

between the result included in the RFAO report and that in the NOCTS case file; the NOCTS 

value is assumed to be correct because it is the handwritten urinalysis record and is also the 

larger of the two values. The resulting dose is < 1 mrem (0.15 mrem). The Excel file RFP H-3 

dose calculations – data.xlsx contains the information above as well as the data used for the 

analysis.

Conclusion

The RFAO report (SRDB 8790) of a 1.5-Ci tritium release on August 30, 1974 from a 

contaminated shipping container (“pressure cooker”) provides air survey, bioassay, and smear 

survey results that can be used to model similar releases. Such a model can be scaled to 

account for the source term and applied to incidents prior to the 1973 environmental tritium 

release when such tritium monitoring data are not available for Rocky Flats. The baseline 

information from these data can also be used to model the pre-1973 background tritium 

environment at Rocky Flats because the 1974 release described in the RFAO report occurred 

close enough in time to the seminal 1973 tritium event that many or most of the procedures 

and workplace practices had only begun to transition to account for the new sensitivity to 

tritium and its potential impact on Rocky Flats operations.

The number and nature of reported tritium release events, both before and after 1973, provide 

the basis for assumptions of pre-1973 workplace release frequencies, quantities and chemical 

forms. The parameters of this model can then be used to estimate pre-1973 bounding doses to 

Rocky Flats workers from estimates of the tritium background environment and tritium release

incidents, particularly those involving contaminated shipping containers.

Part III presents an example tritium dose reconstruction that provides dose estimates for the 

pre-1973, 1973, and post-1973 time periods as well as doses and probabilities of causation for 

four types of cancer. The results are summarized below.
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Page 21 of 38

 Pre-1973: Using the largest reported result collected after the August 30, 1974 incident, the 

resulting dose is < 1 mrem (0.15 mrem). Assuming one incident per day at 0.15 mrem for 

250 days results in a dose of 37.5 mrem/year for the pre-1973 time period.

 1973: Using the bioassay samples collected after tritium incident associated with 

contaminated scrap in mid- to late-April 1973 resulted in a maximizing dose of 84 mrem and 

is applied as a bounding estimate of all unmonitored workers. This dose is more precise

than the estimate in the evaluation report, but is still maximizing. 

 Post-1973: A co-worker study using data from NOCTS for 1974 and 1975 resulted in an 

annual dose of less than 1 mrem; therefore, no dose will be assigned for unmonitored 

tritium after 1973.
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Page 22 of 38

PART II:

Rocky Flats Tritium Dose

Assignment for 1973 and Later

by

E. M. Brackett

Dose Assignment for 1973

The report, Investigation of the Tritium Release Occurrence at the Rocky Flats Plant (SRDB 

24165, pdf p. 16), describes a 1973 incident that prompted the site to sample a number of 

workers for tritium exposure. A shipment of scrap plutonium from LLNL was discovered to have 

been contaminated with tritium. This material was processed at the Rocky Flats Plant from 

April 9 to 25, 1973 in Building 779A. Because it was not immediately identified as being 

contaminated, monitoring of potentially-exposed individuals did not begin until late September 

1973.

Two hundred fifty people were sampled following the discovery; this included all employees 

who worked in areas in which the contaminated scrap was processed or who were involved in 

the processing of wastes from this scrap. Due to the large sample load, raw urine samples were 

first analyzed in many of the cases. It was noted that the counting efficiency was only about 3% 

for these analyses, and that the corrections made for spectral shift could lead to abnormallyhigh readings. Nineteen employees were initially identified as having elevated tritium levels in 

their urine. These samples were distilled and re-analyzed. Upon this recheck, fourteen of these 

employees were found to be below the 10,000 pCi/L action level established by the site. The 

[redacted for privacy] most-exposed individuals were identified and details of their potential 

exposures, including bioassay results, are included in the investigation report. [redacted for 

privacy]individuals is in NOCTS. ORAUT reviewed the results of the [redacted for 

privacy]workers who exceeded the 10,000 pCi/L action level; this review is presented in 

Attachment A.
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Page 23 of 38

The best estimates for the [redacted for privacy] cases reviewed in Attachment A are 

summarized in Table A-5 below. Tritium contamination was associated with plutonium scrap 

material; therefore, H-3 doses will be assigned to all individuals who were monitored for 

plutonium in 1973. Because monitoring began several months after the potential start of 

exposure, the largest assessed dose (84 mrem) will be assigned. 

Table A-5: Summary of Intake Assessments for the RFP 1973 Incident

Case Intake Date Intake (μCi) Dose (mrem)

A 1973 38.7 2.6

B 1973 28.1 1.9

C 1973 21.3 1.4

D 1973 1070 72

H 1973 1240 84

Dose Assignment for 1974-1975

ORAUT performed a co-worker study using data from NOCTS for 1974 and 1975. There are 38 

individuals with tritium data in 1974 and 37 in 1975. ORAUT-OTIB-0075, Use of Claimant 

Datasets for Coworker Modeling, provides justification and guidance. 

When assessing tritium intakes for most sites, it is assumed that intake potential exists only 

while tritium bioassay monitoring is being performed because monitoring is cheap, easy, and 

requires only spot samples, thus presenting less of a burden than other forms of bioassay on 

both the employer and the employee. Because tritium was not of primary concern at RFP and 

was present only as a potential contaminant on equipment, a given individual was not placed 

on a routine sampling program. Instead, a program was established whereby one-tenth of the 

urine samples collected for plutonium analysis were also analyzed for tritium content (SRDB 

111267, letter from RFP General Manager to RFAO AEC Manager) as well as the collection of 

samples when there was a particular concern. Samples available in NOCTS for these two years 

indicate that analyses were performed throughout the year, with most individuals sampled only 

once.
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Page 24 of 38

For the purpose of the co-worker study, it was assumed that each worker had the potential to 

be exposed at a constant level throughout the year in which the urine sample was collected. 

The 95th percentile was used because one-tenth of the population was sampled. The co-worker 

study for 1974 -1975 yielded doses of 0 mrem for everyone. The file Tritium for 1974-1975 

coworker.xlsx contains the assumptions employed in the study. 

Dose Assignment after 1975

For later years, there are 11 or fewer individuals in NOCTS with tritium data; this is insufficient 

for performing a co-worker study. Results for these years are consistent with those from the 

previous years and show a general decreasing trend. The intake rate from the 1974-1975 

co-worker study (i.e., 0 mrem - see above) will apply to these years; therefore, no additional 

dose due to tritium, as it relates to the assessment performed in this analysis, will be assigned 

after 1973.

Example Dose Reconstruction

Part III presents an example tritium dose reconstruction that provides dose estimates for the 

pre-1973, 1973, and post-1973 time periods as well as doses and probabilities of causation for 

four types of cancer.
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Page 25 of 38

Attachment A:

Rocky Flats 1973 H-3 Dose Assignment

by

Elizabeth Brackett

As discussed in Part II of this white paper, ORAUT reviewed the results of the [redacted for 

privacy] workers who exceeded the 10,000 pCi/L action level for tritium following a 1973 

incident. This attachment provides the results of ORAUT’s review and proposes a method for 

the assignment of H-3 doses in 1973.

Background

Investigation of the Tritium Release Occurrence at the Rocky Flats Plant (SRDB 24165, pdf p. 16) 

describes an incident in 1973 that prompted the site to sample a number of workers for 

potential H-3 exposure. The initial location of the contaminated scrap was identified as 

Building 779A, Room 154, in mid- to late-April. The waste stream from the processing of this 

material was also contaminated, providing opportunities for intake of H-3 at later dates. The 

collection of samples from a tritium-contaminated water bubbler on September 19 and 

September 25, 1973 were also identified as possible opportunities for intakes.

The contamination problem was not immediately identified; therefore, urinalysis began several 

months after the potential start of intakes. Samples were collected from about 250 employees. 

All employees who worked in areas in which the contaminated scrap was processed, or who 

were involved in the processing of wastes from this scrap were included in the urinalysis 

program. 

Exhibit 14 of the referenced report contains a section on Personnel Exposure Data. The 

following is an excerpt (SRDB 24165, pdf p. 122):

SAMPLING PROTOCOL

Dow began by sampling urines from all employees who were thought to have had the best 

chance of being exposed to tritium. As of October 15, 1973, about 250 employees have been 

tested. Dow is continuing to trace leads to other possible exposure and will sample them as 

they are found. Dow intends to sample many employees who have had only a remote 
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Page 26 of 38

chance of coming in contact with tritium. Dow also tests the urine of any employee who 

requests this whether or not they are candidates for exposure.

ACTION LEVELS

An "action level" of 10,000 pCi/l was tentatively chosen for resampling. This level was 

chosen for several reasons such as:

1. An article by Fitzsimmons indicated that people wearing tritiated watches could excrete 

levels of 10,000 pCi/l.

2. A calculation of worst possible circumstances indicate that an employee would have to 

exceed levels of 23,000 pCi/l before any permissible yearly levels of whole body radiation 

would be exceeded.

3. The sample load was such that Dow could handle resampling only a limited number of 

employees on a frequent basis. It turned out that a relatively small number were over 

10,000 pCi/l but a large fraction were in the 5,000 and 10,000 pCi/l range.

4. Without predistilling the urine samples the counting efficiency drops to about 3% and 

the corrections made for spectral shift can lead to abnormally high reading.

5. With a large sample load, counting time devoted to each sample must be restricted so 

that 10,000 pCi/l might be considered lowest detection limit available under the present 

circumstances.

All samples above 10,000 pCi/l are redone by counting the distillate of the original sample.

[redacted for privacy] workers with H-3 urinalysis results exceeding the action level of 10,000 

pCi/L were identified. Results from these [redacted for privacy] workers are reviewed here. 

Fourteen other workers initially exceeded the 10,000 pCi/L level but fell below this upon 

recount (as noted above, the distillates of the original samples were counted). 

Dose Assessment

Information about the [redacted for privacy]workers with the largest H-3 sample results 

(including H-3 urinalysis results and brief work histories) is included in the referenced SRDB 

document. This information was used to assess the doses to the affected workers and is 

displayed in italics in the sections below.
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues

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Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 27 of 38

All [redacted for privacy] cases had initial samples that were not distilled, with one to five later 

distilled samples. In general, the two sets of results were not consistent, with the distilled 

samples yielding lower values. This is to be expected given the site discussion above (see Item 

4). The pre-distilled results were used in the development of this white paper because there 

were more results available and they yielded claimant-favorable doses.

The following assumptions were employed in this assessment:

 Equal weight to all samples (measurement error the same for all samples)

 Only pre-distilled samples used for fits (these are shown as blue dots in the figures; distilled 

samples appear in red and are not used in the analysis)

 H-3 in the form of tritiated water (HTO)

 IMBA model for inorganic H-3, as described in Guidance on Use of IMBA Software for DOE 

Safety Applications (DOE, 2006)

 Injection intake (for modeling with IMBA)

 Intake dates based on worker information and examination of fit to urine sample results

The [redacted for privacy] workers identified as having the largest H-3 urinalysis results are 

assessed below. Text in italics indicates an excerpt from the incident report.

Case A

Case A worked in Room [redacted for privacy]) from [redacted for privacy], until the 

[redacted for privacy].

He was involved in the [redacted for privacy] [redacted for privacy]of the parts in question 

from [redacted for privacy], along with Cases [redacted for privacy]. He was not involved in 

any of the following special projects:

a. May 8, 1973, Window Change

b. June 16, 1973, TV Camera Installation

c. August 21, 1973, Rotary Blower Installation

He was involved in taking samples from a [redacted for privacy]on [redacted for privacy], 

1973. On [redacted for privacy], this was done without a rubber glove.
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues 

This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 28 of 38

From this history, it would appear the most likely exposure occurred on [redacted for 

privacy]. If an exposure had occurred between [redacted for privacy], 1973, it is likely that 

both Cases [redacted for privacy]would have been exposed to the same source, and 

subsequently, excreted the same quantities of tritium. 

The incident report also says: 

In Case A, a history of his work assignment and his urine results for the first two weeks 

indicate that he sustained a recent exposure. At the present time he is excreting tritium with 

an elimination half life of less than 10 days. According to Sanders and Snyder, this is the 

pattern of elimination from an exposure up to 90-days post exposure. 

The statement that his intake appears to be recent agrees with current models for HTO intakes. 

If an intake is assumed from [redacted for privacy], a very poor fit to the data is obtained, as 

shown in Figure A-1. 

Figure A-1: Case A Chronic Intake of HTO from [redacted for privacy], 1973 

Based on the worker’s history and the bioassay result pattern, an acute intake was assumed to 

have occurred on [redacted for privacy], 1973. Using the results of samples collected from 

[redacted for privacy], and applying a uniform error to each of the samples, the intake is 38.7 

μCi. The corresponding dose is 2.6 mrem. These samples are presumed to be pre-distilled 

because later samples from Oct. 5 to Oct. 12 are labeled as “distilled.” This yields a very good 

fit to the pre-distilled results (see Figure A-2). 
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues 

This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 29 of 38

Figure A-2: Case A Acute Intake of HTO on [redacted for privacy]1973

Case B 

He has worked in [redacted for privacy]since [redacted for privacy]. He was in the room 

when [redacted for privacy]that contained tritium. 

Assumption of a chronic intake from [redacted for privacy] (date of first urine sample) yields an 

intake rate of 0.33 μCi/d (for a total intake of 28.1 μCi) and provides a reasonable fit to the 

results (see Figure A-3). The dose is 1.90 mrem. 

Figure A-3: Case B Chronic Intake of HTO from [redacted for privacy], 1973 

Assumption of an acute intake on [redacted for privacy] [redacted for privacy] yields an intake 

of 7.28 μCi. This fit (see Figure A-4) is almost identical to the first scenario. 
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues 

This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 30 of 38

Figure A-4: Case B Acute Intake of HTO on [redacted for privacy] 1973

A single acute intake on his [redacted for privacy] day in the area ([redacted for privacy]) yields 

an intake of 720 μCi and a dose of 49 mrem (see Figure A-5). 

Figure A-5: Case B Acute Intake of HTO on [redacted for privacy] 1973
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues 

This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 31 of 38

The single acute intake on [redacted for privacy] does not provide a good fit to the later predistilled results. The first two scenarios (chronic intake from [redacted for privacy] and acute 

intake on [redacted for privacy]) provide similar fits that reasonably follow the pattern of the 

pre-distilled samples. The chronic intake yields a larger intake so it is used for the best 

estimate. 

Case C 

He worked in [redacted for privacy] since [redacted for privacy]. He was not in the room 

when [redacted for privacy] containing tritium. 

Given that the worker did not start in the area until [redacted for privacy], an acute intake was 

assumed on this date (see Figure A-6). Using only the pre-distilled sample results, his intake is 

21.3 μCi with a dose of 1.4 mrem. 

Figure A-6: Case C Acute Intake of HTO on [redacted for privacy] 1973

If a chronic intake is assumed to have started on his [redacted for privacy] day of potential 

exposure ([redacted for privacy]) and continued until the date of his [redacted for privacy]

sample ([redacted for privacy]), the resulting intake is 0.24 μCi/d for a total intake of 7.08 μCi. 

This fit is shown in Figure A-7. 
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues 

This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 32 of 38

Figure A-7: Case C Chronic Intake of HTO from [redacted for privacy] 1973 

The two fits are very similar, so the acute intake is selected as the best fit as it results in a dose 

that is more favorable to the claimant. 

Case D 

He worked in [redacted for privacy], between [redacted for privacy], 1973. He has not been 

exposed to tritium since [redacted for privacy]. 

Case D submitted samples on only three days, although there are two results on two of those 

days. In one instance, one of the samples was distilled; on the other day, there is a note stating 

“repeated with sample channel ratio.” On the latter day, the results differ by a factor of almost 

two; the larger of these results is assumed to be the pre-distilled analysis and is used for the 

intake assessment. An assumed chronic intake from [redacted for privacy] (last date of 

incident) yields an intake of 71.2 μCi/d for a total intake of 1070 μCi (see Figure A-8). The 

resulting dose is 72 mrem. 
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues 

This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 33 of 38

Figure A-8: Case D Chronic Intake of HTO from [redacted for privacy], 1973 

A chronic intake from [redacted for privacy] yields an intake rate of 8.84 μCi/d for a total intake 

of 581 μCi (39 mrem), as shown in Figure A-9. 

Figure A-9: Case D Chronic Intake of HTO from [redacted for privacy] 1973 

Because there are few samples and the results follow no specific pattern, there is little 

difference between the fits. Therefore, the acute intake is assigned because it yields the larger 

dose. 
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues

This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 34 of 38

Case H

He came in contact with the possible source of tritium on [redacted for privacy] 1973.

No other information is included in the report. The conclusion in the report is: (It is expected 

that, as a result of a review of his work history and urinalysis data, a dose assignment of less 

than 3 rem will be made.) However, no follow-up information is available.

Because the only available information indicates that an intake would have occurred on 

[redacted for privacy] an acute intake was modeled (see Figure A-10). The resulting intake is 

1240 μCi with a dose of 84 mrem. 

Figure A-10: Case H Acute Intake of HTO on [redacted for privacy], 1973
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues

This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 35 of 38

Recommendation

The best estimates for each case are summarized in Table A-6. Tritium contamination was 

associated with plutonium scrap material; therefore, H-3 doses will be assigned to all 

individuals who were monitored for plutonium in 1973. Because monitoring began several 

months after the potential start of exposure, the largest assessed dose (84 mrem) will be 

assigned. 

Table A-6: Summary of Intake Assessments for the RFP 1973 Incident

Case Intake Date Intake (μCi) Dose (mrem)

A 1973 38.7 2.6

B 1973 28.1 1.9

C 1973 21.3 1.4

D 1973 1070 72

H 1973 1240 84

Reference

DOE, 2006, Guidance on Use of IMBA Software for DOE Safety Applications, DOE-HS-0002, U.S. 

DOE, Washington D.C.; December 2006 (SRDB 33212)
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues

This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 36 of 38

PART III:

Example RFP Tritium Dose Reconstruction

by

Mutty Sharfi

Employee Information

Cancer Description: Lung (ICD-9: 162); diagnosed 12/31/2000

Prostate (ICD-9: 185); diagnosed 12/31/2000

BCC (ICD-9: 173); diagnosed 12/31/2000

SCC (ICD-9: 173); diagnosed 12/31/2000

Year of birth: [redacted for privacy]

Gender: Male

Smoking: Never Smoked

Ethnicity: “White, non-Hispanic”

Employment Information

Start date: [redacted for privacy]

End date: [redacted for privacy]

Occupation: Unknown 

Dosimetry Data: None

Organ Dose Assessed

Table A-7: Organ Dose Assessed

Cancer External Organ Used Internal Organ Used

Lung Lung Lung

Prostate Urinary Bladder Heart Wall1

Skin Skin Skin

Source: ORAUT-OTIB-0005

1 Non-metabolic organ with the highest dose
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues

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Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 37 of 38

External Dose

Not applicable for tritium exposures.

Internal Dose

 Pre-1973: The 1.5-Ci tritium release from a contaminated shipping container occurred on 

August 30, 1974. The largest reported bioassay result (SRDB 8790) collected after the 

incident was used to assess the potential exposure from this release. The resulting dose is 

was about 0.15 mrem. Assuming this event occurred every workday of the year (250 times 

a year), the resulting annual dose would be about 38 mrem/year.

 1973: A tritium incident associated with contaminated scrap occurred in Building 779A, 

Room 154, in mid- to late-April 1973. Because of this incident, the site sampled a number 

of workers for potential H-3 exposure (SRDB 24165). An analysis of these bioassay samples 

resulted in a maximizing dose of 84 mrem and is applied as a bounding estimate of all 

unmonitored workers. The assessment of the bioassay data for the 1973 incident includes 

all potential exposures for the year. The assumption of an acute intake bounds any 

potential underlying chronic exposure. 

 Post-1973: ORAUT performed a co-worker study using data from NOCTS for 1974 and 1975 

in accordance with ORAUT-OTIB-0075, Use of Claimant Datasets for Coworker Modeling. 

The 95th percentile annual dose was less than 1 mrem. Therefore, no dose will be assigned 

for unmonitored tritium after 1973.

Uncertainty 

All doses are applied as a constant distribution. 
White Paper: Follow-up Efforts on SEC-00192 RFP Tritium Issues

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Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor.

Page 38 of 38

Summary 

The assessment methods presented in this report define the methods by which a dose estimate 

can be determined for the evaluated worker class. These methods support NIOSH’s conclusion 

that the operationally-related internal dose for the evaluated worker class can be bounded. A 

summary of the doses and probability of causations are provided in Table A-8 below.

Table A-8: Example RFP Tritium DR - Summary of Doses and Probabilities of Causation

Cancer External (rem) Internal (rem) Total (rem) Probability of Causation

Lung 0.000 0.616 0.616 3.99%

Prostate 0.000 0.616 0.616 1.45%

Skin BCC 0.000 0.616 0.616 3.38%

Skin SCC 0.000 0.616 0.616 0.47%